Triboelectric nanogenerator (TENG) devices have promising applications in the fields of wearable power technology, motion monitoring, physiological monitoring, and human–computer interaction. A challenge is making TENG devices according to scalable techniques enabling multidirectional action with high sensitivity and accuracy. Herein, we present a scalable nanotechnology, delivering a dual-electrode semi-cylindrical fiber TENG (DE-TENG), resembling a combination of Merkel disks (MD) and Ruffini endings (RE) skin elements responding to different tactile stimuli. The upper and lower silver nanowire-based (Ag NWs) electrodes are encapsulated in polydimethylsiloxane (PDMS) to form single-electrode modes in a DE-TENG configuration with asymmetric responsivity for both electrodes. For energy harvesting applications, a long-term stable output results, and the instantaneous output power of the upper electrode reaches a maximum value of 0.64 μW at an external load resistance of 100 MΩ, with the output power of the lower electrode being four times smaller. Moreover, for motion recognition with low forces (below 0.15 N), a very high sensitivity is realized in the state of the art, with the upper and lower electrode layers of the DE-TENG material providing 9 V/N and 15 V/N. In this context, the DE-TENG material was mounted onto a finger to accurately identify a bending or touching motion, benefiting from a strong signal at least by one of the electrodes, and further exploited in a multi-channel wearable e-fabric with stimulus-dependent position recognition. In combination with deep learning, coupling of multi-channel signals from such dual-electrode TENG can improve the accuracy of motion recognition up to 99.84

The integration of biotechnology and information technology has created a growing demand for high-performance flexible bio-electrodes. However, existing conductive polymer systems often struggle to simultaneously achieve high electrical conductivity, excellent stretchability, and high-resolution circuitry that are essential for soft bioelectronics. To address these challenges, we developed a light-curable, elastomeric bio-electrode consisting of a dual-network conductive hydrogel system combining poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) with a photo-crosslinkable Pluronic hydrogel. Utilizing digital light processing (DLP)-based three-dimensional (3D) printing technology, this bio-electrode can be rapidly prototyped with customized, high-resolution electrode structures and tailored packaging. Subsequent acid treatment induces molecular chain rearrangement within the electrode, resulting in a denser network topology and significantly enhanced electrical conductivity. Consequently, these flexible electrodes exhibit excellent electrical performance exceeding 300 S/m, while maintaining remarkable flexibility and stretchability. The fabricated electrodes demonstrate good biocompatibility and are capable of delivering electrical stimulation to biological tissues or recording cortical neural signals. This approach provides an efficient strategy for customizing high-performance flexible bio-electrodes, holding significant promise for future medical applications.

Fused deposition modeling (FDM) is a widely used 3D-printing technique because of its low cost, ease of operation, and rapid prototyping capability. However, the polymer portfolio available for FDM remains limited, and polypropylene (PP), despite its broad industrial relevance as a commodity polymer, is still underutilized because crystallization during cooling induces a marked reduction in specific volume, leading to shrinkage and, when spatially non-uniform, to warpage. Therefore, regulating crystallization kinetics and crystal structure is essential for reducing warpage and improving the dimensional stability of P-based printed parts. In this research, PP/PA6 composites with an in situ PA6 (Polyamide 6) microfiber structure were fabricated by FDM. The viscosity ratio of the selected PA6 dispersed phase to the PP matrix was evaluated under processing-relevant shear rates using capillary rheometry, confirming that eta(PA6)/eta(PP) < 1 and thereby supporting the feasibility of in situ fibrillation. The formation of PA6 microfibers in the PP matrix was verified via SEM, and shish-kebab as well as hybrid shish-kebab structures were observed. Crystallization and crystalline structure results further showed that PA6 microfibers promote heterogeneous nucleation and orientation of the PP phase, leading to increased PP crystallinity, elevated crystallization temperature, accelerated crystallization, and the formation of beta-crystals. Consequently, the FDM-printed composites exhibited markedly improved dimensional stability, tensile strength and low-temperature impact toughness compared with molded controls, demonstrating that in situ microfibrillation is an effective strategy for enhancing the performance of PP-based FDM materials.

Injection molding is widely used for polymer components, yet producing dimensionally accurate poly(lactic acid) (PLA) parts remains challenging because shrinkage and warpage arise from thermal contraction, crystallization-induced densification, and relaxation of frozen-in amorphous structure. Post-molding annealing can increase crystallinity and heat resistance, but may also induce secondary shrinkage and embrittlement. Here, two commercial injection-molding PLA grades with different crystallization behavior were processed under identical molding and packing conditions, while only the annealing protocol was varied between 60 degrees C and 120 degrees C. DSC showed different crystallization tendencies after thermal-history erasure, with crystallinity of approximately 3% for PLA_a and 20% for PLA_c, although as-molded specimens showed similar crystallinity of 14%-17%. Isothermal DSC confirmed faster crystallization of PLA_c, with half-times 3-5 times shorter than PLA_a at 100 degrees C and 120 degrees C. Annealing increased crystallinity to approximately 68% for PLA_c and 50% for PLA_a after 3 h at 120 degrees C. However, PLA_a showed stronger secondary shrinkage, reaching 2%-2.3%, whereas PLA_c remained below 1%. Enthalpy-recovery analysis, POM, SEM, MFI, TGA, and FTIR demonstrate that annealing produces a grade-dependent trade-off between crystallinity, dimensional accuracy, and mechanical performance. Impact strength peaks at 90 degrees C, whereas tensile performance decreases at 120 degrees C, confirming crystallinity alone cannot predict dimensional stability reliably.

Triboelectric nanogenerators (TENGs) are emerging as self-powered sensors, while relying on (i) non-sustainable, oil-based materials and (ii) external timing circuits or machine learning back ends. Here, we report a bio-based, 4D-printed α-helix shape memory TENG (H-STENG) that integrates sustainable material design, programmable architecture, and interpretation ready multimodal sensing. A PLA/PHA/chitosan composite was engineered through meso-scale morphology regulation and interfacial hydrogen-bonding and amide interactions, yielding improved toughness and shape memory recovery ( 90

Flexible piezoelectric composite films with superior machinability, long-term stability, and efficient lowfrequency energy harvesting capabilities are increasingly crucial for the emerging high technologies, including the Internet of Things (IoT) as well as human-machine interaction (HMI) systems. Nevertheless, the pristine polyvinylidene fluoride (PVDF) suffers from deficient piezoelectric coefficients and high circuit loss, which is not conducive to highly efficient utilization. Here, a hierarchically structured piezoelectric film is engineered by synergistically integrating poly(vinylidene fluoride-co-hexafluoropropylene) P(VDF-HFP), highly polar barium titanate nanoparticles (BT NPs), and breakdown-resistant hydroxyapatite nanowires (HAP NWs), combining the high responsiveness of piezoelectric ceramics with the flexibility and low dielectric loss of polymers, making it ideal for wearable electronics. Featuring a polarized layer/breakdown-resistant layer/polarized layer sandwich architecture, the prepared film enhances dipole alignment and dielectric stability via polymer-filler mesoscopic interactions, thus achieving synergistic improvement in piezoelectric and ferroelectric properties. The optimized film exhibits a maximum open-circuit voltage of 31.5 V, short-circuit current of 0.7 mu A, power output of 2.78 mu W/cm2, and piezoelectric coefficient of 22.8 mV/V. This work establishes a novel paradigm for next-generation flexible devices, potentially promoting healthcare monitoring, IoT systems, and high-precision sensing electronics.

Abstract Fused Filament Fabrication (FFF) offers a promising route for fabricating thermally conductive polymer composites, but high filler loadings often impair mechanical performance and processability. Here, an immiscible PP/PA6/BN ternary system was developed by integrating selective filler localization with FFF-induced domain alignment. Because of the stronger affinity between BN and PA6, BN platelets preferentially enriched in PA/BN-rich domains rather than dispersing randomly in the PP matrix. During FFF deposition, these domains were elongated and partially interconnected along the main raster direction, forming anisotropic thermal-transport pathways. Compared with compression-molded PP/PA/BN and binary PP/BN, the printed PP/PA/BN composite showed enhanced directional thermal conductivity while retaining mechanical integrity and printability. Morphological, WAXD/XRD, and rheological analyses indicate that thermal transport arises from BN orientation, PA/BN-rich domain interconnection, and multiphase interfacial effects. This work provides a morphology-regulation strategy for printable thermally conductive composites.

Abstract Consecutive ammonolysis and hydrogenation are promising chemical recycling routes for the depolymerization of polyamide (PA). A challenge is the design of the reaction conditions, leading to sufficiently fast unzipping with limited side reactions. In the present contribution, a kinetic model is developed, consisting of 15 reactions, with the rate coefficients tuned for a given catalyst combination. This is done considering, in a first step, the isolated ammonolysis and, in a second step, the isolated hydrogenation of the small-molecule compounds N-hexylhexanamide and hexanamide, respectively. In a third step, the mixed small-molecule system is considered, and, in a fourth step, diffusional limitations are taken into account for the ammonolysis with PA chains to facilitate a good description of the balance of scission and recombination reactions. To validate the kinetic model, size exclusion chromatography (SEC) traces of the polymer at various stages of the ammonolysis-hydrogenation reaction are modeled and systematically compared with experimental data. It is demonstrated that the kinetic model provides a first step toward the in silico selection of the most suited ammonolysis-hydrogenation reaction conditions for the efficient recycling of PA in view of scale-up targets. This achievement brings depolymerization technology closer to a wider application in our striving for a circular implementation of this important PA waste stream. Further investigation of catalyst concentration and carrier dependencies, as well as the presence of contaminations, is, however, necessary.

Blood clots containing nutrients can promote multiple tissue repair, but their use in nerve repair is limited due to the risk of red blood cell-related neurotoxicity. We presented a cell motility-based selective hydrogel for the rapid generation of nerve-repairing blood clots with negligible red blood cell toxicity. This hydrogel, derived from gelatin and featuring a nanocolloidal structure, permitted the migration of neural stem cells (NSCs) while blocking red blood cells, which was mediated by differential cell motility within its nanostructure. Following the rapid generation of blood clots, the hydrogel with blood-derived growth factors promoted the recruitment of endogenous NSCs. The nanocolloidal structure in the hydrogel facilitated the migration and differentiation of NSCs to repair the neural tissue. In rats and porcine models, the hydrogel could induce rapid hemostasis and promote nerve repair in vivo, leading to improved neurological function. This work provides a proof of concept for the generation of nerve-repairing clots using a cell motility-based selective hydrogel, which would inspire future methods for nerve repair.

To speed-up polymer processing design, it is worthwhile to enhance the applicability of our polymer melt computational fluid dynamics (CFD) tools. Essential is the more representative embedding of the rheological first principles in the CFD mesh via an appropriate constitutive model. In the present work, we highlight that the PanThien-Tanner (PTT) constitutive model, with its viscoelastic parameters tuned to rotational and capillary rheometric data, can be coupled to the Ansys Polyflow finite element solver, to simulate 3D isothermal extrudate swell, out of a slit die for a wide variety of thermoplastic polymers. We differentiate between commercial polypropylene (PP), acrylonitrile butadiene styrene polymer (ABS), poly(lactic acid) (PLA), and polyethylene terephthalate glycol (PETG), spanning a wide range of slip (xi), extensional (& varepsilon;), and relaxation time (7) PTT parameters. We additionally include mock materials of which the (xi, & varepsilon;, 7) PTT parameters are (slight) modifications with respect to the PTT parameters of the 4 materials studied to test mathematical boundaries. We highlight that normal stress difference data are critical for the PTT parameter tuning, and computational challenges can be avoided in case the elongational viscosities and mode dependent Weissenberg numbers are not too extreme, i.e. specific combinations of (xi, & varepsilon;, 7) PTT parameters are avoided. The present work contributes to a better linkage of rheological data recording and finite element framework developments toward model-driven

A commercial low viscosity (LV; eta 0= 255 Pa.s), medium viscosity (MV; eta 0= 574 Pa.s) and high viscosity (HV; eta 0 = 1075 Pa.s) polyethylene terephthalate glycol (PETG) grade, and a high mechanical properties (HMP) PETG grade (eta 0 = 437 Pa.s) are characterized to investigate their applicability for filament-based material extrusion, commercially known as fused filament fabrication (FFF), considering 3 printing temperatures and speeds. Additionally, up to 40 m% post-consumer PETG and post-industrial polyethylene terephthalate (PET) waste is blended with each grade, to study their recycling possibilities at the FFF application level. Size exclusion chromatography reveals that the HV and HMP grade undergo chain scission during the consecutive processing steps, whereas for the MV grade post-condensation can occur. The LV grade initially undergoes chain scission and with 40 % post-industrial waste a slight increase in average molar mass is observed. The DSC measurements show that the glass transition temperature is rather fixed during processing and no significant crystallinity is present in the FFF parts containing post-consumer PET. Overall, an increase in printing temperature has a positive effect on the mechanical properties, enhancing the interlayer bonding. Increasing the printing speed generally decreases the quality of the part by introducing discontinuities. The addition of post-consumer waste up to 40 m% does not affect the quality of the parts, except for the LV grade for which (i) 20 m% recycled material even induces a positive effect (tensile modulus increase from 1590 MPa to 1760 MPa) due to better material flow, and (ii) an amount of 40 m% lowers the quality (tensile modulus decrease from 1590 MPa to 1460 MPa) reminding the increase in average molar mass, affecting negatively the flow behaviour. The addition of post-consumer waste is not recommended specifically for the HMP grade for which a decrease in tensile modulus going from 1380 MPa to 710 MPa is observed. Upon comparing all grades, the LV and HV grade are the most robust regarding changes in printing temperature and speed. However, upon tuning processing parameters, the LV grade can provide the highest tensile and flexural moduli, whereas the HV grade provides the highest impact strength.

This review provides an in-depth look at the key process limitations and (structural) defects encountered in the production of polymer films via film blowing extrusion technology. Film blowing is the most widely used method for producing plastic films across various industries, with its increasing demand driven by flexible packaging needs. Overcoming the challenges of this complex production process is essential for ensuring high quality and meeting the growing demand for modern applications, taking into account polymer circularity. In the first part of this paper, the focus is on conventional films, generally polyolefin single-layer films. Common defects such as bubble instability, gauge variations, wrinkles, melt fractures, optical defects, blocking, and surface imperfections like fish eyes are discussed. The most important causes behind these issues are elaborated on, including various molecular and processing parameters, with this paper also offering practical mitigating strategies. In the second part, the specific process limitations and defect types associated with emerging sustainable film technology are focused on, covering films made from recycled materials, biodegradable polymers, polymer blends, and multilayer and machine-direction oriented (MDO) films. While these innovative films offer significant advantages in terms of sustainability and property enhancement, they also present additional points of attention. Also, effective mitigation strategies for addressing these technical issues are incorporated. Overall, this study provides a comprehensive review of film blowing defects, contributing to improved process control, reduced waste, and the production of high-quality films that meet modern requirements. By identifying the root causes of common defects and discussing viable solutions, this review plays a key role in advancing the efficiency, consistency, and sustainability of film blowing technology by presenting a combined experimental and modelling approach that can be used in future work.

Only limited systematic studies exist on polyethylene terephthalate glycol (PETG) stability during consecutive processing, specifically injection molding. Here, up to five injection molding-shredding reprocessing cycles are investigated, covering four commercial PETG grades corresponding to a melt flow index (MFI) range from 7 to 22 (240 degrees C; 2.16 kg). It is demonstrated that molecular-scale scission degradation reactions take place, affecting the mesoscale thermal and macro-scale mechanical and color properties. SEC, MFI, and InhV analyses revealed chain scission across all grades, with mass average molar masses decreasing up to 20% in most cases and up to 54% for the high-viscosity (HV) grade. In this way, it is showcased that a molecular-driven interpretation of the PETG mechanical recycling potential is highly recommendable, with a key role in molar mass distribution. In most cases, except for the low-viscosity (LV) grade displaying too strong thermal (and thermo-oxidative) degradation, a sufficient flowability can still be realized at high injection molding shear rates. DSC results demonstrate that T g remains stable, with no crystallinity increase developing. TGA analysis showed that thermal stability increases with repeated processing. Yellowing and darkening become more evident, specifically for the medium-viscosity and HV PETG grades. The mechanical properties in the elastic region of deformation do not significantly alter; however, the impact resistance and elongation at break decrease significantly with five processing cycles. Overall, the high-mechanical-property grade, developed for injection molding, is affected by minimal degradation, in a way that still allows the final part to consistently meet or exceed performance threshold values. This work highlights the circularity potential of postindustrial PETG waste, demonstrating that despite some molecular degradation, the material can retain acceptable performance for continued use in high-value applications, if properly designed at the chemical level.

Poly(lactic acid) (PLA) is an important biopolymer facilitating the realization of polymer circularity, with as key application sustainable packaging materials. A downside is its brittleness, requiring physical blend design or chemical modification via reactive extrusion (REX), e.g. (natural) crosslinking by free radical induced grafting (FRIG). The present work highlights that by combining experimental and one compartment coupled matrix-based Monte Carlo (CMMC) analysis a much better quantification of the success of a FRIG-REX process is within reach, mapping for the first time the competition of beta-scission and crosslinking reactions for each molecule present. A model-based quality protocol is proposed and applied with dicumyl peroxide (DCP) as conventional radical initiator, considering an extensive experimental data set from the molecular to the material level. It is showcased that chemical modifications are always obtained for both the lower and higher molar mass region of the molar mass distribution (MMD), with only for sufficiently high DCP amounts a clear crosslinking as also confirmed by mechanical analysis. The protocol involves the unique quantification of the molecular structure of both the soluble and insoluble molecules during REX, supported by model validation based on size exclusion chromatography, Soxhlet extraction, and rheological data. Thermogravimetric analysis is shown to be a less recommendable experimental technique, due incomplete DCP conversion. The current work opens the door to the faster design of mechanical recycling processes and its upgrading through REX via model-based design.

Poly(lactic acid) (PLA)-based materials, with e.g. automotive, packaging, agricultural, and electronic applications, still display a too high brittleness, inhibiting the full exploitation of biopolymers to replace abundantly applied oil-based polymers. Herein, a novel (reactive) blending strategy is therefore presented, in which deliberately degraded polyhydroxy-butyrate (dPHB) is mingled with PLA in the presence of maleic anhydride (MA), allowing plasticizing and grafting via radicals, e.g. formed by shear or the addition of dicumyl peroxide. For the comparison of the final properties, fused filament fabrication (FFF) is employed as a manufacturing technique. Based on the analysis of molecular and thermal properties, flow behavior, and grafting efficiency, it is revealed that blending with dPHB and not the original PHB, in the presence of MA, improves the processability with as extra advantage a sustainable method for PHB material usage. The bio-composite with dPHB and MA (75 m% PLA) possesses excellent mechanical properties, with specifically the elongation at break much higher than that of neat PLA, or a blend of PLA and PHB (and MA). The enhanced properties are due to effective dispersion of dPHB within the bio-composite and the crosslinking/chain extension with MA, opening the door to more sustainable materials beyond conventional PLA and PHB.

A challenge for self-powered flexible devices with applications in the field of Internet of Things (IoT) is their fast and cost-effective production, ensuring accurate display and recognition of many motion trajectories for intelligent control. Herein we present a fully self-powered triboelectric sensor made via extrusion-based additive manufacturing (AM), efficiently embedding post-purified long silver nanowires (AgNWs) in thermoplastic elastomer (TPU). The deformable AgNW stretchable electrodes make the stress transfer stable throughout the device, to achieve outstanding self-powering properties. The roughness of the surface is enhanced by sandpaper treatment design, which significantly improves triboelectric features with voltage increases from 4.9 to 16.7V. The extrusion-made composite sensor enables the development of a highly reliable artificial intelligence (AI) driven motion recognition system, with a detection reliability as high as 97%. This accuracy level according to a scalable manufacturing technique offers a promising approach for future IoT devices focused on advanced action interaction and smart wearable electronics.

Polyurethane synthesis can be conducted in several solvents with different overall kinetics, due to variations in the solvent dielectric constant and hydrogen bonding degree. An understanding of solvent effects on the relevant elementary reaction steps is although lacking, as focus has been e.g. at the solvent dependency of initial overall second order rate coefficients (k(overall), (0) values). In the present work, the reaction kinetics for the urethanization of 1-butanol and phenyl isocyanate, which is the monofunctional analogue for polyurethane formation, is therefore studied in three conventional industrial solvents, namely toluene, tetrahydrofuran and dichloromethane. Additionally, two green solvents, namely limonene and dihydrolevoglucosenone (Cyrene), are considered as safety concerns are growing. Rate coefficients are determined for the non-catalyzed, and the alcohol-, isocyanate- and carbamate-catalyzed pathways, performing parameter tuning per solvent at different temperatures. It is shown that the alcohol- and carbamate-catalyzed pathways display the highest rate coefficients. Moreover, a solvent model is constructed out of the tuned parameters, so that elementary rate coefficients and activation energies can be predicted for a general solvent based on its dielectric constant and number of hydrogen bonding groups, saving tremendous time in experimental synthesis and analysis. Solvent model validation has been performed via different formats, including a comparison of conventional rate coefficients and those obtained from the solvent model (typical maximal deviation of 60 %), using a sixth solvent, namely deuterated chloroform, not included in the training of the solvent model, and koverall, 0 literature data for over 15 solvents. Emphasizing on the green solvents, limonene seems promising, as the rate coefficients are the highest. The current work opens thus the door to a fast sustainable solvent screening for solution-based chemistries, specifically solution polymerization.

Polymethacrylate derivatives are widely used in various industrial applications. The incorporation of degradable thioester bonds in polymethacrylates to achieve degradability/recyclability upon disposal is a challenge. Unfortunately, the most efficient thionolactone to insert cleavable thioester linkages does not copolymerize with methacrylates. We show that a small amount of the thionolactone can be inserted into polymethacrylates by the use of methyl acrylate or N-phenyl maleimide as an auxiliary third comonomer. We confirmed the selective degradation of the copolymer via aminolysis. The intriguing incorporation of the thionolactone via the formation of triads is demonstrated using Monte Carlo simulations and such method is also used to optimize the synthesis conditions. Copolymers of 60,000 g.mol-1 is obtained that could be degraded with a 25-fold reduction of size, confirming the model-based insights and opening the pathway to degradability for polymethacrylates. This approach is also successfully extended to poly(butyl methacrylate), and water-soluble poly(oligo(ethyleneglycol) methacrylate) for biomedical applications.

With the advent of 5G technology, electronic components are increasingly undergoing miniaturization and integration. Nevertheless, these components exhibit significant thermal output during operation, which can detrimentally impact their functional integrity and longevity. The solution for this challenge might be achieved by the industrially relevant fabrication of thermally conductive polymer matrix composites for heat exchangers. It was recently shown that one of the most efficient heat conductors can be produced from composites with a segregated three-dimensional filler structure. However, the rapid fabrication of these types of composites remains a pressing yet challenging task. This study introduces the preparation of thermoplastic polyurethane (TPU)/polydopamine-modified graphene (GPDA) flexible composites featuring segregated thermal conductive structure (s-TPU/GPDA), utilizing a convenient method based on extrusion-based additive manufacturing. The printed s-TPU/GPDA exhibits relatively high thermal conductivity at low filler contents while retaining certain insulating properties. Specifically, the thermal conductivity of s-TPU/GPDA reached 0.87 W/(mK) along the printing direction at a low GPDA loading of 3.5 wt %. The electrical conductivity of s-TPU/GPDA is approximately three levels lower than that of the composites without modified graphene. In addition to, FFF can rapidly fabricate s-TPU/GPDA composites in various shapes, exhibiting sufficient mechanical properties. Consequently, this study provides a facile strategy to fabricate thermally conductive composites with a segregated structure via an efficient FFF 3D printing technique.

Roadmap to obtain acrylate-specific rate coefficients/Arrhenius parametersrr via PLP-SEC.